<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        /* .parent>div   亲儿子 */
        .parent>div{
            color: slateblue;
            font-size: 20px;
        }
        /* .parent div  后面所有的div */
        .parent div{
            font-size: 30px;
        }
    </style>
</head>
<body>
    <div class="parent">
        <div>child</div>
        <div>child2</div>
        <ul>
            <li><div>child3</div></li>
            <li><div>child4</div></li>
        </ul>
    </div>
</body>
</html>